refactor(download): mark episode downloaded instead of deleting

Change _remove_episode_from_missing_list to set is_downloaded=True
and populate file_path via EpisodeService.mark_downloaded, instead of
deleting the Episode row. Preserves download history so queries can
distinguish series with downloaded episodes from completely unwatched
series.

- Pass serie_folder to construct file_path
- Look up series_id via AnimeSeriesService.get_by_key
- Update tests to mock mark_downloaded path
- Document episode lifecycle in docs/DEVELOPMENT.md

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

docs/DEVELOPMENT.md

@@ -82,6 +82,22 @@ The download queue prevents duplicate entries at two levels:
 - 5-minute cooldown prevents rapid re-triggers
 - Checked at start of `_auto_download_missing()`
 
+### Episode Lifecycle
+
+Episodes transition through states stored in the `episodes` table:
+
+| State | `is_downloaded` | `file_path` | Description |
+|-------|----------------|-------------|-------------|
+| Missing | `False` | `NULL` | Episode not yet downloaded |
+| Downloaded | `True` | Set | Episode exists on disk |
+
+**State Transitions:**
+1. **Missing → Downloaded**: When download completes, `_remove_episode_from_missing_list()` calls `EpisodeService.mark_downloaded()` to set `is_downloaded=True` and populate `file_path`. The episode record is NOT deleted.
+
+**Query Implications:**
+- `get_series_with_missing_episodes()`: Filters for `is_downloaded=False` to find series with undownloaded episodes
+- `get_series_with_no_episodes()`: Finds series with `is_downloaded=False` episodes but NO `is_downloaded=True` episodes (completely unwatched series)
+
 ### Mocking the Download Queue
 
 When testing components that use the download queue:

src/server/services/download_service.py

@@ -14,6 +14,7 @@ import uuid
 from collections import deque
 from concurrent.futures import ThreadPoolExecutor
 from datetime import datetime, timezone
+from pathlib import Path
 from typing import TYPE_CHECKING, Dict, List, Optional
 
 import structlog
@@ -68,6 +69,7 @@ class DownloadService:
             progress_service: Optional progress service for tracking
         """
         self._anime_service = anime_service
+        self._directory = anime_service._directory
         self._max_retries = max_retries
         self._progress_service = progress_service or get_progress_service()
         
@@ -210,30 +212,33 @@ class DownloadService:
         series_key: str,
         season: int,
         episode: int,
+        serie_folder: Optional[str] = None,
     ) -> bool:
-        """Remove a downloaded episode from the missing episodes list.
+        """Mark a downloaded episode as downloaded instead of deleting it.
         
         Called when a download completes successfully to update both:
-        1. The database (Episode record deleted)
+        1. The database (Episode record marked is_downloaded=True)
         2. The in-memory Serie.episodeDict and series_list cache
         
         This ensures the episode no longer appears as missing in both
-        the API responses and the UI immediately after download.
+        the API responses and the UI immediately after download,
+        while preserving the download history.
         
         Args:
             series_key: Unique provider key for the series
             season: Season number
             episode: Episode number within season
+            serie_folder: Series folder name (required for file_path)
             
         Returns:
-            True if episode was removed, False otherwise
+            True if episode was updated, False otherwise
         """
         try:
             from src.server.database.connection import get_db_session
-            from src.server.database.service import EpisodeService
+            from src.server.database.service import EpisodeService, AnimeSeriesService
             
             logger.info(
-                "Attempting to remove missing episode from DB: "
+                "Attempting to mark episode as downloaded in DB: "
                 "%s S%02dE%02d",
                 series_key,
                 season,
@@ -241,28 +246,63 @@ class DownloadService:
             )
             
             async with get_db_session() as db:
-                deleted = await EpisodeService.delete_by_series_and_episode(
+                # Get series by key to find series_id
+                series = await AnimeSeriesService.get_by_key(db, series_key)
+                if not series:
+                    logger.warning(
+                        "Series not found for key: %s", series_key
+                    )
+                    return False
+                
+                # Get episode by series_id, season, episode_number
+                ep = await EpisodeService.get_by_episode(
                     db=db,
-                    series_key=series_key,
+                    series_id=series.id,
                     season=season,
                     episode_number=episode,
                 )
-                if deleted:
+                if not ep:
+                    logger.warning(
+                        "Episode not found in DB: %s S%02dE%02d",
+                        series_key,
+                        season,
+                        episode,
+                    )
+                    return False
+                
+                # Construct file_path if serie_folder provided
+                file_path = None
+                if serie_folder:
+                    season_folder = f"Season {season}"
+                    file_path = str(
+                        Path(self._directory) / serie_folder / season_folder
+                    )
+                
+                # Mark episode as downloaded instead of deleting
+                updated = await EpisodeService.mark_downloaded(
+                    db=db,
+                    episode_id=ep.id,
+                    file_path=file_path or "",
+                )
+                
+                if updated:
                     logger.info(
-                        "Successfully removed episode from DB missing list: "
+                        "Marked episode as downloaded in DB: "
+                        "%s S%02dE%02d, file_path=%s",
+                        series_key,
+                        season,
+                        episode,
+                        file_path,
+                    )
+                else:
+                    logger.warning(
+                        "Failed to mark episode as downloaded: "
                         "%s S%02dE%02d",
                         series_key,
                         season,
                         episode,
                     )
-                else:
+                    return False
-                    logger.warning(
-                        "Episode not found in DB missing list "
-                        "(may already be removed): %s S%02dE%02d",
-                        series_key,
-                        season,
-                        episode,
-                    )
             
             # Update in-memory Serie.episodeDict so list_missing is
             # immediately consistent without a full DB reload
@@ -273,8 +313,8 @@ class DownloadService:
             try:
                 self._anime_service._cached_list_missing.cache_clear()
                 logger.debug(
-                    "Cleared list_missing cache after removing "
+                    "Cleared list_missing cache after marking "
-                    "%s S%02dE%02d",
+                    "%s S%02dE%02d as downloaded",
                     series_key,
                     season,
                     episode,
@@ -282,10 +322,10 @@ class DownloadService:
             except Exception:
                 pass
             
-            return deleted
+            return True
         except Exception as e:
             logger.error(
-                "Failed to remove episode from missing list: "
+                "Failed to mark episode as downloaded: "
                 "%s S%02dE%02d - %s",
                 series_key,
                 season,
@@ -1119,12 +1159,13 @@ class DownloadService:
                 # Delete completed item from download queue database
                 await self._delete_from_database(item.id)
                 
-                # Remove episode from missing episodes list
+                # Mark episode as downloaded in missing episodes list
                 # (both database and in-memory)
                 removed = await self._remove_episode_from_missing_list(
                     series_key=item.serie_id,
                     season=item.episode.season,
                     episode=item.episode.episode,
+                    serie_folder=item.serie_folder,
                 )
                 
                 logger.info(

tests/unit/test_download_service.py

@@ -79,6 +79,7 @@ def mock_anime_service():
     """Create a mock AnimeService."""
     service = MagicMock(spec=AnimeService)
     service.download = AsyncMock(return_value=True)
+    service._directory = "/mock/anime/directory"
     return service
 
 
@@ -731,13 +732,22 @@ class TestRemoveEpisodeFromMissingList:
         download_service._anime_service._app = mock_app
         download_service._anime_service._cached_list_missing = MagicMock()
 
-        # Mock DB call
+        # Mock DB session
         mock_db_session = AsyncMock()
-        mock_delete = AsyncMock(return_value=True)
+        
+        # Mock series returned by get_by_key
+        mock_series = MagicMock()
+        mock_series.id = 1
+        
+        # Mock episode returned by get_by_episode
+        mock_episode = MagicMock()
+        mock_episode.id = 100
 
         with patch(
             "src.server.database.connection.get_db_session"
         ) as mock_get_db, patch(
+            "src.server.database.service.AnimeSeriesService"
+        ) as mock_series_svc, patch(
             "src.server.database.service.EpisodeService"
         ) as mock_ep_svc:
             mock_get_db.return_value.__aenter__ = AsyncMock(
@@ -746,20 +756,30 @@ class TestRemoveEpisodeFromMissingList:
             mock_get_db.return_value.__aexit__ = AsyncMock(
                 return_value=False
             )
-            mock_ep_svc.delete_by_series_and_episode = mock_delete
+            
+            # Mock get_by_key to return series
+            mock_series_svc.get_by_key = AsyncMock(return_value=mock_series)
+            
+            # Mock get_by_episode to return episode
+            mock_ep_svc.get_by_episode = AsyncMock(return_value=mock_episode)
+            
+            # Mock mark_downloaded to succeed
+            mock_ep_svc.mark_downloaded = AsyncMock(return_value=mock_episode)
 
             result = await download_service._remove_episode_from_missing_list(
                 series_key="test-series",
                 season=1,
                 episode=2,
+                serie_folder="Test Series (2024)",
             )
 
-        # DB deletion was called
+        # mark_downloaded was called instead of delete
-        mock_delete.assert_awaited_once_with(
+        mock_ep_svc.mark_downloaded.assert_awaited_once_with(
             db=mock_db_session,
-            series_key="test-series",
+            episode_id=100,
-            season=1,
+            file_path=(
-            episode_number=2,
+                f"{download_service._directory}/Test Series (2024)/Season 1"
+            ),
         )
         # In-memory update happened
         assert 2 not in serie.episodeDict[1]
@@ -807,11 +827,20 @@ class TestRemoveEpisodeFromMissingList:
 
         # Mock DB calls
         mock_db_session = AsyncMock()
-        mock_delete = AsyncMock(return_value=True)
+        
+        # Mock series returned by get_by_key
+        mock_series = MagicMock()
+        mock_series.id = 1
+        
+        # Mock episode returned by get_by_episode
+        mock_episode = MagicMock()
+        mock_episode.id = 100
 
         with patch(
             "src.server.database.connection.get_db_session"
         ) as mock_get_db, patch(
+            "src.server.database.service.AnimeSeriesService"
+        ) as mock_series_svc, patch(
             "src.server.database.service.EpisodeService"
         ) as mock_ep_svc:
             mock_get_db.return_value.__aenter__ = AsyncMock(
@@ -820,7 +849,15 @@ class TestRemoveEpisodeFromMissingList:
             mock_get_db.return_value.__aexit__ = AsyncMock(
                 return_value=False
             )
-            mock_ep_svc.delete_by_series_and_episode = mock_delete
+            
+            # Mock get_by_key to return series
+            mock_series_svc.get_by_key = AsyncMock(return_value=mock_series)
+            
+            # Mock get_by_episode to return episode
+            mock_ep_svc.get_by_episode = AsyncMock(return_value=mock_episode)
+            
+            # Mock mark_downloaded to succeed
+            mock_ep_svc.mark_downloaded = AsyncMock(return_value=mock_episode)
 
             # Process the download
             item = download_service._pending_queue.popleft()